assume cs:code,ds:data

data segment
	db 'Welcome to masm!',0
data ends

code segment
	start:
		;初始化参数
		mov dh,8
		mov dl,3
		mov cl,2
		;指向字符串首地址
		mov ax,data
		mov ds,ax
		mov si,0
		;调用子程序
		call show_str
		;程序返回
		mov ax,4c00h
		int 21h
		
	show_str:
		mov es,0b800h
		mov bx,460h		;偏移到第8行
		
		mov ch,0
		mov cl,ds:[si]
		jcxz ok
		mov ah,00001010b
		mov al,ds:[si]
		mov es:[bx].3[si],ax
		add si,2
		jmp short show_str
	
	ok:	
		ret
code ends
end start